Switch mechanism with unitary biasing, contact, and detent spring

ABSTRACT

A switch mechanism having an actuator or trigger supported to move within a housing between inner and outer positions corresponding to switch on and switch off conditions, separated electrical posts or terminals fixed on the housing spaced from but adjacent the trigger, and a single spring leaf element supported by the housing and urging the trigger to its outer switch off position, the spring leaf element having a detent portion that cooperates with an appropriate detent stop on the housing to releasably hold the trigger in said off position, and the spring leaf elements also having a contact spaced from the electrical terminals in the trigger off position but adapted to engage the terminals in the trigger on position for completing an electric circuit across the terminals.

United States Patent Happe 1 July 11,1972

1541 SWITCH MECHANISM WITH UNITARY BIASING, CONTACT, AND DETENT SPRING [72] Inventor: Reynold llappe, Jefferson City, Mo.

[73] Assignee: McGraw-Edison Company, Elgin, ill.

[22] Filed: April 20, 1971 [21] Appl. No.: 135,618

52 11.5. C1. ..200/1s9 A, 200/157, 200/166 SD 51 rm. (:1, ..rr011| 13/08, 110111 13 52 53 FieldofSearch ..200 157, 159 R, 159A, 166SD,

[56] References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 606,437 7/1960 ltaly ..200/ l 59 R Primary Examiner-Robert K. Schaefer Assisranr xaminerRobert A. Vanderhye Attorney-Charles F. Lind ABSTRACT A switch mechanism having an actuator or trigger supported to move within a housing between inner and outer positions corresponding to switch on and switch off conditions, separated electrical posts or terminals fixed on the housing spaced from but adjacent the trigger, and a single spring leaf element supported by the housing and urging the trigger to its outer switch off position, the spring leaf element having a detent portion that cooperates with an appropriate detent stop on the housing to releasably hold the trigger in said 011' position, and the spring leaf elements also having a contact spaced from the electrical terminals in the trigger ofi position but adapted to engage the terminals in the trigger on position for completing an electric circuit across the terminals.

3Clains,4DrawingFlgures SWITCH MECHANISM WITH UNITARY BIASING, CONTACT, AND DETENT SPRING It is common in small electric appliances to utilize a trigger actuator to shift an on-off switch for operating the appliance. In an electric drill having a pistol grip handle, for example, there is commonly provided a trigger which is actuated by the forefinger of the user to operate the tool. The trigger generally must be held by the user for continuous operation so that upon release of the trigger the tool automatically returns to the off condition.

This invention relates to and an object of this invention is to provide a switch mechanism which is safe and durable in operation to make and break a circuit upon the physical displacement of an actuator or trigger element, but yet which is economically fabricated and easily assembled.

A more detailed object of this invention is to provide a switch mechanism having a single resilient conductive element that returns the trigger actuator element to the switch off position, and serves also as a detent to releasably hold the actuator element in the switch off position, and lastly that has a conductive contact that is displaced upon shifting of the trigger actuator element 'to engage a pair of spaced terminals supported in the housing to thereby complete a circuit across the terminals.

These and other objects will be more fully understood and appreciated after reviewing the following specification, the accompanying drawing forming a part thereof, wherein;

FIG. 1 is a broken away side elevational view showing a typical electric drill in which the subject invention is incorpocated;

FIG. 2 is an enlarged view of the invention, similar to FIG. 1, except showing the switch mechanism in the on position;

FIG. 3 is a perspective view of a preferred spring switch contact element; and

FIG. 4 is a perspective view of the housing terminals of FIGS. 1 and 2.

Referring to FIG. 1, a drill is illustrated having a housing 12 and a rotatable spindle 14 with tool holding chuck 16 being provided thereon. Power means including a motor and gear drive (not shown) are mounted in the housing for output connection with the spindle 14. An electric power cord 22 is connected to the lower part of the pistol grip handle 24, as is typical in many such appliances, and has leads 25, and 27, 28 connected through an appropriate switch contact means 29 to the motor such that actuation of the switch contact means renders the tool operative or inoperative.

Specifically referring to FIGS. 1 and 2, a trigger element 30 is mounted to reciprocate relative to the housing, the trigger having an enlarged contacting portion 32 which extends through an opening 33 in the housing and a rearwardly extended body 34 which is guided between posts 36 from the housing. Stops 38 and 40 on the body portion 34 restrict the movement of the trigger to normal maximum displacement between the switch open, tool off condition when the trigger is released and withdrawn from the housing and the stop 40 engages the posts 36 (FIG. I) and a maximum inner position when the tool is on and the user grasps the switch and squeezes it completely to where the stop 38 would engage the post 36 to restrict further inward movement of the trigger assembly. A finger 42 on the trigger can be positioned behind the face 43 on the housing by slightly lifting the trigger at its exposed face while the trigger is squeezed to hold the switch in the on condition. (FIG. 2).

The power cord lead 25 has a conductive connector 44 thereon which has a cylindrical body 46 split lengthwise and the body is biased into and held snugly in place in an opening in the housing. The second wire 48 also has a like conductor 49 thereon with a split cylindrical body 50 which likewise is received and held fixed relative to the housing. The wires 28 from the power cord and 48 from the terminal 50 extended upwardly for connection to the motor (not shown) in an appropriate manner to provide the power circuit therefor. It will be understood that when means connect the terminals 46 and 50 together a circuit is completed through the motor and that the tool will operate.

The switch element 60 is shown as being one piece which is made of a durable and conductive spring material such as a phosphor bronze. The base 62 of the element is connected to a post 64 and the element extends from the base 62 through a U-bend 66 and then to a intennediate actuating part 68 and end-board detent arm 70. The intermediate actuating part 68 has an opening 71 which receives a rib 72 on the rearward end of the trigger 30 and thereby is laterally confined relative to the trigger. Because of the spring nature of the bend as well as the orientation of the base 62 relative to the post 64, the spring 60 urges the trigger 30 to its outer extended position relative to the housing whereat the stop 40 engages the post 36 as shown in FIG. 1. In this position the detent arm 70 has a bend 74 which is received in a recess provided on the housing structure and the detent arm 70 itself is biased upwardly against the top wall 78 of the housing structure so that the bend 74 becomes lodged against the face 76 with a significant restraining force Free displacement of the trigger inwardly into the housing is thus restricted by this detent force which can be overcome with a significant squeezing efiort against the trigger but this then suddenly releases the trigger. Lastly, a contactor arm 80 extends as the cutout portion from the opening 71 that receives the rib 72 on the inner end of the trigger element, and this contactor arm 80 is provided with a contoured contact 82 at its free end. The contact 82 is normally spaced from the two terminals 46 and 50 when the trigger element 30 is in its outer extended position, but is displaced toward and engages the spaced terminals 46 and 50 when the trigger is displaced to its inner position. This contact 82 is electrically conductive so that its engagement with the terminals 46 and 50 completes an operating circuit through the motor and operates the same as is well known in the art.

As noted above, since detent means 74 and 76 resist rearward shifting of the trigger from its outer extended position, a snap type closing of contact 82 against terminals 46 and 50 does occur once the detent releases to provide long contact life, the user being unable in practice to stop the sudden rearward shifting of the trigger. Upon release of the trigger 30 the spring element 60 returns the trigger to its outer motor off position, where the contact 82 is separated from the terminal posts 46 and 50.

Another aspect of this invention is the simplicity of construction where for example the terminal support posts are molded or formed as integral parts of the particular unit. For example, it is possible and desirable to fabricate the housing unit as of a molded plastic construction where openings can be formed simultaneously with the housing in the interior face thereof. Each terminal conductor 46 and 50 is formed from the split cylindrical element as above noted which can be positioned into the housing opening and be rigidly held therein relative to the housing.

The disclosed switch mechanism is very compact in nature and consists of only two moving parts, the trigger and the integral detent spring and contact element. The particular ele ment thus serves to keep the trigger physically extended, further provides for a snap release detent, and lastly provides a moving contact that engages two spaced terminals to complete a power circuit to operate the appliance. On release of the trigger, the spring returns the trigger to its extended position and opens the contact 82 from the terminals 46 and 50 to terminate the operation of the appliance.

What is claimed is:

1. In an on-off switch mechanism, the combination comprising a housing, an actuating member mounted to move relative to the housing between spaced positions corresponding to on and of? conditions respectively of the switch mechanism, a unitary resilient leaf element secured to the housing and having a spaced cantilevered portion operating against the actuating member and being operable with the resiliency thereof to bias the actuating member to the switch mechanism off position, said unitary leaf element having first and second cantilevered arms that are moved relative to the housing as the actuating member is shifted between its spaced operating positions, a pair of spaced terminals supported in the housing adwherein the electrically conductive contact is fonned on the free end of the first cantilevered arm integrally with said leaf element.

3. A switch mechanism combination according to claim 1, wherein the second cantilevered arm has a free end that is resiliently biased against the housing, and wherein the cooperating detent means is comprised of a tab on the free end of the arm and recess means therefor on the housing. 

1. In an on-off switch mechanism, the combination comprising a housing, an actuating member mounted to move relative to the housing between spaced positions corresponding to on and off conditions respectively of the switch mechanism, a unitary resilient leaf element secured to the housing and having a spaced cantilevered portion operating against the actuating member and being operable with the resiliency thereof to bias the actuating member to the switch mechanism off position, said unitary leaf element having first and second cantilevered arms that are moved relative to the housing as the actuating member is shifted between its spaced operating positions, a pair of spaced terminals supported in the housing adjacent the first arm and an electrically conductive contact carried on the first arm disposed to be separated from the terminals when the actuating member is in the switch mechanism off position but disposed upon shifting the actuating member to the switch mechanism on position to be against both terminals, and cooperating detent means between the second cantilevered arm and housing engaged only when the actuating member is in the switch mechanism off position operable to releasibly hold the actuating member in said position.
 2. A switch mechanism combination according to claim 1, wherein the electrically conductive contact is formed on the free end of the first cantilevered arm integrally with said leaf element.
 3. A switch mechanism combination according to claim 1, wherein the second cantilevered arm has a free end that is resiliently biased against the housing, and wherein the cooperating detent means is comprised of a tab on the free end of the arm and recess means therefor on the housing. 